1. Field of the Invention
This invention relates to the use of hydrophilically substituted enol esters as bleach activators for activating peroxygen compounds, more particularly for bleaching colored stains in the washing of textiles, and to detergents, cleaners and disinfectants containing such bleach activators.
2. Discussion of Related Art
Inorganic peroxygen compounds, more particularly hydrogen peroxide, and solid peroxygen compounds which dissolve in water with elimination of hydrogen peroxide, such as sodium perborate and sodium carbonate perhydrate, have long been used as oxidizing agents for disinfecting and bleaching purposes. In dilute solutions, the oxidizing effect of these substances depends to a large extent on the temperature. For example, with H.sub.2 O.sub.2 or perborate in alkaline bleaching liquors, sufficiently rapid bleaching of soiled textiles is only achieved at temperatures above about 80.degree. C. At lower temperatures, the oxidizing effect of the inorganic peroxygen compounds can be improved by addition of so-called bleach activators which are capable of forming peroxocarboxylic acids under the described perhydrolysis conditions and for which numerous proposals, above all from the classes of N- or O-acyl compounds, for example polyacylated alkylenediamines, more particularly tetraacetyl ethylenediamine, acylated glycolurils, more particularly tetraacetyl glycoluril, N-acylated hydantoins, hydrazides, triazoles, hydrotriazines, urazoles, diketopiperazines, sulfuryl amides and cyanurates, also carboxylic anhydrides, more particularly phthalic anhydride, carboxylic acid esters, more particularly sodium nonanoyloxybenzenesulfonate, sodium isononanoyloxybenzenesulfonate, O-acylated sugar derivatives, such as pentaacetyl glucose, and N-acylated lactams, such as N-benzoyl caprolactam, can be found in the literature. By adding these substances, the bleaching effect of aqueous peroxide liquors can be increased to such an extent that substantially the same effects are obtained at temperatures of only 60.degree. C. as are obtained with the peroxide liquor alone at 95.degree. C.
In the search for energy-saving washing and bleaching processes, operating temperatures well below 60.degree. C. and, more particularly, below 45.degree. C. down to the temperature of cold water have acquired increasing significance in recent years.
At these low temperatures, there is generally a discernible reduction in the effect of known activator compounds. Accordingly, there has been no shortage of attempts to develop more effective activators for this temperature range although the results achieved thus far have not been convincing.
The use of enol esters optionally bearing C.sub.1-5 alkyl or C.sub.2-4 alkenyl groups at the enolic double bond as bleach activators is recommended in European patent applications EP 0 092 932 A1 and EP 0 122 763 A2. It has now surprisingly been found that enol esters bearing at least one hydrophilic group have a distinctly stronger bleach-activating effect.